Sea Ice-Atmosphere Signal of the Southern Oscillation in the Weddell Sea, Antarctica

Composite analysis of weekly ship and shore observations of the Weddell Sea pack ice for extreme events of the Southern Oscillation (SO) occurring in the 1929-62 period reveals strong variations in ice water concentrations in the early and late summer melt season. Substantially reduced ice concentrations (more open water) occur in December and early January of "warm" (El Nino) events (yr(0)) compared with the summer before (yr(-1)), and appear connected with the change to a stronger cyclonic atmospheric circulation over higher latitudes of the South Atlantic. Similarly consistent meteorology sea ice associations appear to characterize the mid- to late summer of warm SO events (yr(0)) compared with yr(0) of "cold" events. There is some evidence that the regionally dependent pressure and wind reversals (and possibly the associated sea ice concentration changes) in the Weddell sector have become more marked during SO events occurring since about the early 1950s. Some corroboration of changes in the sea ice-SO circulation signal over time is afforded by the long-term single point sea ice record for Scotia Bay (Orcadas).